The idea of a Dungeons and Dragons movie only works if you make it a meta commentary on the game itself from the inside, otherwise you are essentially just making a fantasy film, unless you only use the most well known dnd characters which is a total crapshoot because even most people who play them don't know official dnd character names. Paizo tried that with Pathfinder for having each class having a default character but nobody uses them outside of Adventure League and they barely get touched on.

But you could do a DnD movie where a character gets killed off and when they arrive at the next town the actor is there in a different costume. "Barry, no I'm Larry, Barry's Twin Brother, he was a fighter, I'm a ranger." then later die and you meet the same actor in a wig and dress doing a bad woman's voice. "No I'm Marry, Larry and Barry's triplet sister, I'm a cleric because the party apparently doesn't have any healing."

Put in a point where the story fades to black and come back and the actors have bears and are dirty because the session got put on hold for like a month because nobody could get together and now they are picking it back up but their goal has changed because the DM forgot what they were doing and seeing if the audience realizes that's what happened when the group had originally set off to get a chalice but are not getting a necklace at the end.